Common mental disorders pose tremendous health and social burdens in the poorest countries. This Open Forum describes a planning framework to advance effective, sustainable design and implementation of mental health services in these settings. It builds on research in treatment dissemination and on the authors' experience in several initiatives-including the Millennium Villages Project in sub-Saharan Africa and the Partners In Health system in Haiti (Zanmi Lasante). The authors describe a "pyramid of care" approach that specifies five key skill packages to address common mental disorders in low-resource settings and five implementation rules: assess context first; identify priority care pathways and map them across skill packages; specify decision supports, supervision, and triage rules; use quality improvement practices; and plan for sustainability and capacity building. The framework addresses the need for a shared vocabulary and a set of tools to coordinate and compare efforts to scale-up mental health treatment across diverse settings.